Tropical Report

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
800 AM EDT Fri Sep 22 2017

For the North Atlantic…Caribbean Sea and the Gulf of Mexico:

The National Hurricane Center is issuing advisories on Post-Tropical
Cyclone Jose, located a little over a hundred miles southeast of
Nantucket, Massachusetts, and on Hurricane Maria, located just to
the north-northeast of Grand Turk Island.

Tropical cyclone formation is not expected during the next 5 days.

$$
Forecaster Berg

JOSE CONTINUES TO BRING TROPICAL STORM CONDITIONS TO SOUTHERN NEW ENGLAND

Post-Tropical Cyclone Jose Discussion Number 68
NWS National Hurricane Center Miami FL AL122017
500 AM AST Fri Sep 22 2017

Since the last advisory, a small burst of deep convection has been
observed near the center of Jose. The cyclone is still embedded
within a dry environment and located over cold SSTs, so it will be a
little surprising if the convection is maintained for an extended
period of time this morning. The intensity of the post-tropical
cyclone remains 45 kt, based on earlier ASCAT data, and these winds
are likely occuring over open water well to the northwest of Jose’s
center. Surface observations on Martha’s Vineyard, Nantucket, and
Block Island indicate that tropical storm conditions are still
occuring in some locations along the coast. The prior ASCAT pass
also showed a wide area of tropical-storm-force winds just offshore
of Cape Cod, and there is still some opportunity for these winds to
reach the coast this morning. Therefore, the tropical storm
warnings remain in effect, and the NHC will continue to issue
advisories on Jose.

No significant change has been made to the track or intensity
forecast. All of the dynamical models remain in good agreement that
Jose will remain trapped in weak steering flow while gradually
spinning down for the next several days. Although the cyclone has
been drifting west for the past 12 hours, a slow turn back toward
the east should begin sometime later today and continue through at
least day 3. The NHC forecast track is close to the TVCX and HCCA
consensus aids.

KEY MESSAGES:

1. Tropical-storm-force winds, especially in gusts, are occuring
within the tropical storm warning area. These conditions are
expected to continue this morning.

2. Minor coastal flooding is possible along portions of the coast of
southern New England during the next few days. Please see products
issued by local National Weather Service forecast offices.

3. Swells generated by Jose are affecting Bermuda and much of the
U.S. east coast, and will likely cause dangerous surf and rip
current conditions for the next couple of days in these areas.

FORECAST POSITIONS AND MAX WINDS

INIT 22/0900Z 39.7N 68.7W 45 KT 50 MPH…POST-TROPICAL
12H 22/1800Z 39.7N 69.0W 40 KT 45 MPH…POST-TROPICAL
24H 23/0600Z 39.5N 69.0W 40 KT 45 MPH…POST-TROPICAL
36H 23/1800Z 39.2N 68.5W 35 KT 40 MPH…POST-TROPICAL
48H 24/0600Z 38.9N 67.6W 30 KT 35 MPH…POST-TROP/REMNT LOW
72H 25/0600Z 38.5N 67.9W 25 KT 30 MPH…POST-TROP/REMNT LOW
96H 26/0600Z…DISSIPATED

$$
Forecaster Zelinsky

HURRICANE CONDITIONS OCCURRING ON THE TURKS AND CAICOS ISLANDS

Hurricane Maria Discussion Number 25
NWS National Hurricane Center Miami FL AL152017
500 AM EDT Fri Sep 22 2017

Reports from an Air Force Reserve Hurricane Hunter aircraft near
0500 UTC indicated that the central pressure of Maria had risen to
959 mb, accompanied by flight-level winds and SFMR surface wind
estimates that supported an intensity near 110 kt. Since that time,
the cloud tops in the eyewall have cooled, but the eye has become
less distinct in conventional satellite imagery. The initial
intensity is held at 110 kt pending the arrival of the next plane
near 1200 UTC, but it is possible this is a little generous. Maria
is starting to be affected by 15-20 kt of southwesterly vertical
wind shear, with the first sign of this being a decrease in
convective banding in the western semicircle.

The large-scale models forecast some shear to persist through the
forecast period, and as a result the intensity guidance predicts a
gradual weakening. In addition, after 48 h the forecast track takes
the center of Maria over waters that were cooled significantly by
the passage of former Hurricane Jose. Based on these factors, the
new intensity forecast calls for a slow weakening during the first
48 h similar to the previous forecast, then calls for more weakening
than previously forecast as the cyclone reaches the colder waters.

The initial motion is 315/6. Maria will be moving between the
subtropical ridge to the east and a broad trough over the
southeastern United States and the adjacent Atlantic waters during
the next several days. This pattern should cause the hurricane to
turn north-northwestward and then northward during the next 72 h.
The track guidance is tightly clustered during this part of the
forecast, and the new forecast track is an update of the previous
track. After 72 h, the guidance becomes a little more divergent.
The Canadian and ECMWF models are on the left side of the envelope
showing a generally northward motion, while the GFS is on the right
side showing a north-northeastward motion. This part of the
forecast track is nudged just a little to the left of the old
forecast and the consensus models to account for the ECMWF/Canadian
forecasts.

KEY MESSAGES:

1. Flash flood warnings continue in portions of Puerto Rico due
to persistent heavy rainfall from Maria’s trailing rainbands.
Everyone in Puerto Rico should continue to follow advice from local
officials to avoid these life-threatening flooding conditions.

2. Swells from Maria are expected to begin reaching the coast of
the southeastern United States today. These swells are likely to
cause dangerous surf and life-threatening rip currents along the
coast for the next several days, even with Maria forecast to remain
well offshore over the western Atlantic Ocean.

FORECAST POSITIONS AND MAX WINDS

INIT 22/0900Z 21.6N 70.6W 110 KT 125 MPH
12H 22/1800Z 22.6N 71.1W 105 KT 120 MPH
24H 23/0600Z 24.2N 71.7W 105 KT 120 MPH
36H 23/1800Z 25.9N 72.2W 100 KT 115 MPH
48H 24/0600Z 27.4N 72.3W 95 KT 110 MPH
72H 25/0600Z 29.5N 72.0W 85 KT 100 MPH
96H 26/0600Z 31.5N 71.0W 75 KT 85 MPH
120H 27/0600Z 33.5N 70.5W 65 KT 75 MPH

$$
Forecaster Beven